summary: Researchers found a correlation between Alzheimer’s plaques and hearing loss while conducting experiments in mice. In one transgenic mouse model of Alzheimer’s disease, aged mice exhibited hearing changes similar to those observed in humans with Alzheimer’s disease.
The decisive factor appears to be the location of amyloid-beta protein plaques, and hearing impairment is thought to be associated with plaques on the auditory brainstem.
This finding provides a new approach for tracking the progression of Alzheimer’s disease and may inform diagnostic practice.
Important facts:
- This study included two different transgenic mouse models of Alzheimer’s disease, both designed to produce amyloid beta protein, a major component of plaques associated with Alzheimer’s disease.
- The study revealed that plaques in specific parts of the brain, such as the hippocampus and auditory cortex, do not appear to have a significant impact on hearing loss. The determining factor appeared to be the presence of plaques in the auditory brainstem.
- Researchers found that plaques on the auditory brain stem interfered with this region’s ability to coordinate responses to sound, potentially explaining why some Alzheimer’s patients experience hearing symptoms. there is a possibility.
sauce: University of Rochester
Science lends itself to questions, changing hypotheses, and accidental discoveries. Recently, in the White Lab at the University of Rochester’s Del Monte Neuroscience Institute, neuroscience graduate student Dasian Na was looking at data for a project, but instead discovered something unexpected. He found that locations in the brain where Alzheimer’s-related plaques were found may contribute to hearing loss.
Na had performed hearing tests on mice with the protein plaques found in Alzheimer’s disease and amyloid beta, the main component of the protein. While looking at two different transgenic mouse models of the disease, he found that in one model, called 5xFAD, older mice had hearing changes similar to those seen in Alzheimer’s patients. . Other models did not show these hearing changes, nor did young mice in the 5xFAD group.
“This was a serendipitous observation,” said Nah, lead author of the paper containing these findings. Frontiers of Neuroscience.
“Both mouse models had the amyloid-beta protein, but plaques were found in different locations, which may explain why hearing loss differed between groups.”
The researchers found plaques in the hippocampus and auditory cortex of the brains of aged mice in both models. However, mice with altered hearing also have a small amount of plaques in the auditory brainstem, suggesting that this region may be sensitive to the destruction by plaques seen in Alzheimer’s disease. . Researchers found that plaques impair the brainstem’s ability to coordinate its response to sound.
“This may explain why patients with Alzheimer’s have hearing symptoms,” said Dr. Patricia White, professor of neuroscience and lead author of the study.
“We believe that plaque location may be more important for hearing loss, which can be assessed with amyloid PET imaging, making it a potential biomarker for tracking disease progression.” There is a possibility.
“Our data also suggest that routine auditory brainstem response assessments may be diagnostic.”
Additional authors include Dr. Jingyuan Zhang, Dr. Holly Beaulac, Dr. Dorota Piekna-Przybylska, Dr. Paige Nicklas, and Amy Kiernan, of the University of Rochester Medical Center.
Funding: This study was supported by the National Institutes of Health, National Institute on Aging.
About this Alzheimer’s disease and hearing loss research news
author: Kelsey Smith Hejduk
sauce: University of Rochester
contact: Kelsey Smith Hejduk – University of Rochester
image: Image credited to Neuroscience News
Original research: open access.
“Increased central auditory gain in 5xFAD Alzheimer’s disease mice as an early biomarker candidate for Alzheimer’s disease diagnosisBy Daxiang Na et al. Frontiers of Neuroscience
overview
Increased central auditory gain in 5xFAD Alzheimer’s disease mice as an early biomarker candidate for Alzheimer’s disease diagnosis
Alzheimer’s disease (AD) is a neurodegenerative disease with no cure. All current therapies require accurate diagnosis and staging of AD to ensure adequate care. Central auditory processing disorder (CAPD) and hearing loss are associated with Alzheimer’s disease and may precede the development of Alzheimer’s dementia. Therefore, CAPD may be a potential biomarker candidate for AD diagnosis.
However, little is known about how the pathological changes in CAPD and AD are correlated. In this study, we investigated auditory changes in Alzheimer’s disease using a transgenic amyloidosis mouse model. The AD mouse model was crossed with a mouse strain commonly used for auditory experiments to compensate for the recessive accelerated hearing loss in the parental background.
Auditory brainstem response (ABR) recordings revealed profound deafness, decreased ABR wave I amplitude and increased central gain in 5xFAD mice. By comparison, these effects were milder or reversed in APP/PS1 mice.
Longitudinal analysis reveals that increased central gain precedes decreased ABR I wave amplitude and hearing loss in 5xFAD mice, which may be due to central nervous system lesions rather than peripheral losses suggests. Pharmacological enhancement of cholinergic signaling with donepezil reversed the central increase in 5xFAD mice.
After increased central gain, aged 5xFAD mice developed deficits in hearing sound pips in the presence of noise, consistent with CAPD-like symptoms in AD patients. Histological analysis revealed deposition of amyloid plaques in the auditory cortex of both mouse strains.
However, plaques were observed in the upper auditory brainstem, particularly in the inferior colliculus (IC) and medial geniculate body (MGB), in 5xFAD mice but not in APP/PS1 mice. This plaque distribution is consistent with histological findings in AD patients and correlates with age and increased central gain.
Overall, we concluded that auditory changes in an amyloidosis mouse model correlated with amyloid deposition in the auditory brainstem and could be initially reversed by enhanced cholinergic signaling.
We suggest that changes in ABR recordings associated with increased central gain prior to AD-related hearing impairment may be used as early biomarkers for AD diagnosis.
